Friday, 26 November 2010

As part of its "monitoring birds" series, SEO/BirdLife has just brought out a new booklet on the shy Common Snipe (Gallinago gallinago), one of many species that are all too often overlooked by government authorities and researchers and receive attention only from a few stalwart (and almost always unpaid) amateur sleuths. This interesting booklet can now be downloaded in PDF version. Only a hundred-odd pairs of Snipe breed in Spain. About ten are still hanging on in Ourense, hitherto the Spanish population's stronghold before Antelas Lake dried up, and there are about 60-105 pairs in hay meadows in the Avila sierras, just behind the now snowy Gredos peaks in the north of Extremadura. This magnificent fieldwork is still underway for the authors have unearthed new pairs in 2010 in zones of Ávila where the book had previously cited them (M. Lorenzo, pers. comm.). From here we want to add our own pennyworth, because although the book records the Snipe as absent from the Sierra de Guadarrama, César Clemente (SEO-Cáceres) has proven their presence in Navas del Marqués (Ávila), where he was lucky enough to watch the magnificent drumming display flight in spring 2008.

Saturday, 20 November 2010

The above sequence of photos shows a Black Bullhead Catfish (Ameiurus melas) being caught and eaten by a Cormorant (Phalacrocorax carbo). The photos would obviously win no prizes; neither is the observation anything out of the ordinary, since Cormorants are skilful fishers. The surprising factor is the place, a recently opened and shallow gravel pit where you wouldn't expect to find fish of this size yet. And the worrying aspect is that this gravel pit should already be occupied by an invasive species that is quickly spreading in native waters. In every single visit to this gravel pit we have seen successful Cormorant captures of Black Bullhead Catfish, which is also a prey species of Little Grebe and several heron species (Grey Heron, Little Egret, Great White Egret).

The Black Bullhead Catfish, native to North America belongs to the siluriformes order, which does not exist naturally on the Iberian Peninsula. Its biggest Extremadura populations are in the catchment areas of the rivers Tiétar and Alagón. As in so many other cases it has been introduced deliberately and also as the accidental result of escaped livebait. There are also records of another introduced North American catfish in Extremadura, the Channel Catfish (Ictalurus punctatus) dating from the 1990s in the Badajoz reservoirs of Zújar and La Serena. Luckily there have been no more recent records. Lastly a third siluriforme, the European Catfish, also called Wels Catfish or Sheatfish(Silurus glanis), has also found its way into some Extremadura reservoirs. In Cedillo there was a one-off record from the 1990s and another was caught in Alcántara reservoir in 2008, this time within the Monfragüe National Park. In this case we are not talking about any old fish but a species that can grow 2.5 metres long and weigh over 100 kg! Native to the large rivers of Central Europe, it is a rapacious predator that has become highly prized by some fishermen, who insist on introducing it illegally wherever they can. Something akin to releasing lions or tigers in our dehesas.

The boom in introduced species contrasts sharply with the lamentable situation of our native species. Largely overlooked, these small denizens of our rivers often turn out to be surprisingly diverse. The latest studies continue to differentiate new species with tiny ranges; endemics have been discovered for Salamanca, Guadalajara and Málaga. In Extremadura the most similar case is the ray-finned species Cobitis vettonica, called Vettonian Spined-loach (Cobitis vettonica) in Spanish. It is exclusive to the catchment area of the river Alagón from which it takes its name, straddling the provinces of Salamanca and Cáceres, with its biggest populations in the rivers Alagón, Jerte and Ambroz.

Tuesday, 16 November 2010

Bird migration is a fascinating subject. We watch with awe as birds of all sizes clock up journeys of thousands of kilometres under their own steam in only a few days, living each year in two (or sometimes even three) different continents. The new technologies, especially satellite tracking, have revolutionised our knowledge of migration. We can now keep abreast of it day by day, find out the routes used, the speed and height flown at, the stopover points, etc. All you need to do is drop into a website. Sitting comfortably in front of a PC screen, anyone nowadays can thrill to the epic journeys, not always with a happy outcome, of storks, raptors, gulls and waders, courtesy of generous promoters who furnish us with the information. In Spain, unfortunately, this information is not always so forthcoming. It's easier to keep track of birds marked in Holland, Estonia or even Australia than others born in our own country. As always, happily, there are exceptions. WWF and Fundación Biodiversidad have set up a magnificent website we can dip into at will to marvel at the odyssey of four Segovia Egyptian Vultures, one immature male and three adults (two females and one male). This is the second year of the project. Unfortunately, one of the stars of the first journey, the male Atlas, died poisoned in Siruela (Badajoz). The female Vega survived and is once more being spied on this second time around.

We recommend dropping into the website "el viaje del alimoche" before reading the following nutshell account of the journey of Sahel, the only inmature of these four Egyptian Vultures and the only one that passed through Extremadura. All of them are now in Mauritania, in the same zone where they wintered in 2009, after clocking up 3000 km, sometimes flying at 95 km/hour at a height of 2000 metres. Sahel was the first to leave the Hoces de Riaza (Segovia) on 30 August, the three adults then following suit on 12 and 15 September. It first headed west for Salamanca, where it spent some time near Ciudad Rodrigo. The real journey begun on 5 September when it headed south through the Sierra de Gata (Descargamaría, Santibáñez el Alto), the Cáceres plains (Coria, Portaje, Garrovillas, Cáceres) and the province of Badajoz (Mérida and Zafra). On 7 September Sahel entered Andalucía; after overflying Sevilla it reached the Straits of Gibraltar on 8 September. In two days it had crossed the whole 400 km of Extremadura and needed only four to leave Spain completely. On 9 September its stepped up its pace, arriving at the Moroccan Atlas mountains after crossing the strait in a nonstop 500 km stage. Here it rested up a while to gird its loins for the Sahara crossing. On 12 September it entered the great desert, passing through Algeria and Mali before reaching its final destination in the Mauritanian Sahel on 20 September. A sixteen-day voyage. Its virtual companions took a little longer, reaching the same destination between 27 and 30 September. Best of luck to all of them. We'll see you next spring.

Friday, 12 November 2010

Every month this blog publishes a list of the most notable observations of the previous month. Even the most cursory glance at one of these monthly lists shows a striking fact: the sheer number of these observations that are made in reservoirs. The percentage was particularly high last October, at about 80% of the total. As ecologists, however, we always come out strongly against any new reservoir project. Why the paradox? If reservoirs are so bad why do we spend so much time birdwatching in them? This begs a question we cannot afford to shirk.

The answer is at once very simple and very difficult, simple in principle and difficult as it actually pans out in practice. Basically, reservoirs might be good wintering and passage sites but they are very poor breeding grounds. The huge sheet of water seen from the air pulls down many migrating birds for a pit-stop, especially wildfowl and other aquatic birds like ducks, geese and waders. On winter nights these reservoirs can also be excellent roosting sites, especially for such an iconic Extremadura bird as the Crane, and we all flock to reservoirs like Rosarito and Sierra Brava to watch gobsmacked the huge incoming flocks of these magnificent birds. As breeding sites, however, reservoirs are pretty hopeless. The everchanging banks give lakeside vegetation no chance to take hold, making it very difficult or impossible for any phragmites reedbeds to build up, a sine qua non for typical wetland species to breed there. There are exceptions of course. Arrocampo, due to its particular purpose of cooling the Almaráz nuclear power plant, has to hold its water levels fairly steady. This has allowed at least a substantial reedmace bed to grow there, if not a phragmites reedbed. This has now become home to breeding species like Purple Heron and Purple Swamphen, scarce elsewhere in the region. In Rosarito Reservoir, straddling the Cáceres-Toledo border, there is now a large and stable Cormorant colony. Little Terns sometimes try to breed there, without much success. In general, however, reservoirs provide few birds with breeding territory but they wipe out huge swathes of it for others. The amount of breeding grounds that are lost by such a sudden and aggressive act as flooding a whole river valley is incalculable and irreversible.

Hence the dichotomy: reservoirs can be great wintering sites (by day and night) and migration stopover points, but at what cost to the birds that previously bred in the area? The huge rafts of ducks floating on the Sierra Brava reservoir are a staggering sight. But most of them don't even feed there, simply resting up there before winging out to feed on the surrounding rice fields. The Cranes that nowadays roost in our reservoirs have almost certainly been roosting in the general area for centuries; it's just that nowadays they are concentrated in an area that, well managed, offers them greater security. (Badly managed, reservoirs might even turn out to be harmful for them. Take the case of Rosarito. Even though it is a SPA site, fishermen are allowed to drive their cars right to the water's edge and quads and motorbikes scramble on the sand when water levels are low, precisely when the Cranes are arriving tired from their autumn odyssey and are in greatest need of rest). The rare waders that turn up on the muddy edges of our reservoirs, however interesting they might be (and we all might twitch for them as a once-in-a-lifetime event) are largely irrelevant. They could almost certainly have rested up equally well in thousands of other sites. But the Great and Little Bustards that have been driven out for good?

Neither is it all about birds. Damning rivers has dire effects for fish-life; hence Extremadura's rather poor ichtyofauna. Fish are in fact the most threatened group of vertebrates in the region. Our otters are probably also hard put to deal with all the shifting water levels and changes in the region's water courses. The biggest known heronry in Extremadura was drowned for ever beneath the waters of the Sierra Brava reservoir, now a paradoxical birdwatching Mecca.

The damage is particularly severe when a reservoir project involves a site of great importance for a threatened species, like the Monteagudo project in the River Tiétar (Ávila), which would destroy breeding territory of Imperial Eagle. If, god forbid, it should go ahead, I guess that in 10 or 20 years, like the fallible mortals we are, always looking for the quick fix, we would all wend our way there to tick off the latest rarity that turns up on spring or autumn passage. But I'm equally sure that all of us, put on the spot, would gladly swap this juicy but one-off sighting for the Imperial Eagle or even the buzzard or scores of scrub warblers that bred there in the past and have now had to look for other outlets in an ever-dwindling range of possibilities.

Wednesday, 10 November 2010

Following a Wallcreeper blog entry published a few days ago we received an old Monfragüe Wallcreeper record. The list of birds furnished by the observer, Alan Parker, included an astonishing sighting of a Honey Buzzard (Pernis apivorus) at Salto del Gitano on the same day as the Wallcreeper (11 January 1989). The record is 100% reliable. Alan himself mentioned in his notes how totally unexpected it was to see a Honey Buzzard in January. There is no other Extremadura record at a similar date, though we're not sure whether or not the record is unprecedented at national or European level.

In Extremadura Honey Buzzards are summer visitors, arriving in early May and leaving by September. There have been occasional sightings in February (23 and 27/02/2000) and March (13/03/99 and 19/03/99). Source: Anuario Ornitológico de Extremadura.

Tuesday, 9 November 2010

A list of the most notable records sent to the GOCE forum in October 2010 (compiled by Sergio Mayordomo). We'd like to include non-GOCE sightings as well but no one sends any. Why not send in yours to seo.caceres@gmail.com.

Last post-breeding observations- Osprey: one at Valuengo Reservior(Badajoz) on 15/10 (A. Núñez Ossorio). Another seen at Los Canchales Reservior(Badajoz) on 16/10 (A. Matador) and 20/10 (Godfried Schreur).- Booted Eagle: one pale morph at Moraleja (Cáceres) on 05/10 (C. Clemente)and a dark morph at Mérida (Badajoz) on 18/10 (Á. Sánchez).- Montagu's Harrier: one near Montijo (Badajoz) on 05/10 (Á. Sánchez).- Hobby: one at El Gordo (Cáceres) on 17/10 (J. Briz and V. Risco).- House Martin: nine at La Codosera (Badajoz) on 24/10 (G. Schreur).- Sedge Warbler: two at Granja de Granadilla (Cáceres) on 10/10 (R. Montero).- Reed Warbler: one at Talaván Reservoir(Cáceres) on 22/10 (S. Mayordomo).- European Nightjar: one at San Vicente de Alcántara (Badajoz) on 23/10 (G. Schreur).- Common Redstart: one at Guijo de Coria (Cáceres) on 06/10 (S. Mayordomo).- Short-Toed Eagle: one at Almendralejo (Badajoz) on 18/10 (R. Vicente).- Subalpine Warbler: one at Badajoz (Badajoz) on 02/10 (J. C. Paniagua)- Purple Heron: one at Badajoz (Badajoz) on 07/10 (J. C. Salgado), a young bird at Casas de Belvís (Cáceres) on 09/10 (J. Briz) and one bird in Granja de Granadilla on 10/10 (R. Montero).- Yellow Wagtail: three at Galisteo (Cáceres) on 21/10 (J. Prieta and S. Mayordomo).- Pied Flycatcher: several at Plasencia (Cáceres) on 15/10 (E. Palacios and S. Mayordomo) and four at La Albuera (Badajoz) on 23/10 (J. C. Paniagua).- Whinchat: one bird at Jerte Reservoir(Cáceres) on 20/10 (J. Prieta) and another at Galisteo (Cáceres) on 21/10 (S. Mayordomo).- Pallid Swift: 4 birds at Piornal (Cáceres) on 13/10 and one at Plasencia on 17/10 (J. Prieta).

Earliest winter visitors- Dunnock: several at Monfragüe on 18/10 (J. Prieta)- Hen Harrier: two at Llerena (Badajoz) on 18/10 and one male at Granja de Torrehermosa (Badajoz) on 21/10 (A. Núñez Ossorio).- Greylag Goose: two flocks of 14 and 16 birds at Los Ibores (Cáceres) on 12/10 (J. Briz and V. Risco) and 5 birds at Valdecañas Reservoir(Cáceres)on 15/10 (Á. Sánchez).- Water Pipit: 6 birds at Galisteo (Cáceres) on 13/10 (J. Prieta).- Bullfinch: two birds at Villanueva de la Vera (Cáceres)on 23/10 (D. Langlois and S. Langlois) and one at San Vicente de Alcántara (Badajoz) on the same date(J. Gordillo).- Golden Plover: four at Aldea del Cano (Cáceres) on 27/10 (G. Schreur) and six at Valdeíñigos (Cáceres) on 30/10 (R. Guzmán).- Reed Bunting: one at Talaván Reservoir(Cáceres) on 29/10 (G. Schreur).- Merlin: one juvenile/female at Galisteo (Cáceres) on 04/10 (S. Mayordomo)and another at Guijo de Coria (Cáceres) on 13/10 (J. Prieta).- European Starling: over 15 birds at Guijo de Coria (Cáceres) on 13/10 (J. Prieta).- Crane: thirteen over Trujillo (Cáceres) on 09/10 (Martin Kelsey). Estimation of about 17,822 birds in the central zone (Badajoz/Cáceres) on 29/10 (M. Gómez Calzado).- Siskin: several at Piornal (Cáceres) on 07/10 (J. Prieta) and one at Villanueva de la Vera (Cáceres) on 13/10 (D. Langlois).- Stock Dove: 3 birds seen at Galisteo (Cáceres) on 19/10 (R. Montero) and 90 in flight on 26/10 (S. Mayordomo).- Goldcrest: two at Piornal (Cáceres) on 26/10 (J. Prieta).

Sunday, 7 November 2010

On 31 October 2010 the Fundación Xavier de Salas brought together in Trujillo a sizeable group of Extremadura bloggers, mainly nature photographers but also news bloggers (birds in our case and other groups dealing with orchids and geology). The central moment came with the presentation of a small book containing a selection of up-and-running online blogs. Most of these blogs are for the personal expression of one blogger; Aves de Extremadura is one with a group character. This means that all of you who collaborate in Aves de Extremadura in any way, whether with observations or photos, should rightfully consider yourselves to be participants in this book. The biggest source of info, images, ideas and inspiration is without doubt the GOCE forum, a meeting point that is now recording an almost frenetic rate of activity. No fewer than 643 messages in October and 248 in the first eight days of November!! GOCE has never before been in such rude health. The growth of the forum has coincided in time with the launch of this blog (and another one of SEO-Cáceres) so the two events may well be causally related. Aves de Extremadura received almost 2000 hits last month and has been chalking up a daily mean of 100-150 hits lately.

- In the last ten years the Los Hornos Wildlife Rescue Centre (Centro de Recuperación Los Hornos) in Sierra de Fuentes has taken in and cared for 938 Griffon Vultures, 217 Monk Vultures and 32 Egyptian Vultures. Malnutrition cases have soared since 2005.

- In the whole region, according to government figures, there are 859 pairs of Monk Vulture and 166 pairs of Egyptian Vulture. Sierra de San Pedro and Monfragüe boast the biggest colonies of Monk Vulture, with 352 and 315 pairs respectively; the colony of Sierra de Gata is home to 54 pairs [N.B. in none of these cases is the year mentioned].

- Since 2003 the Regional Council of Extremadura (Junta de Extremadura) has verified 98 cases of vulture poisoning.